Heh, this is a strange co-incidence. It was only a couple of days ago I first ran across janka hardness ratings on a page dedicated to charting which common cabinetmaking wood offcuts make the best firewood (seriously) (oh, and I wasn't actively looking for firewood information it was one of those sites you 'stumble across')
What immediately strikes me are that this is side hardness as opposed to end hardness, the two can be very different and on the other site there were lots of examples where a type of wood with greater side hardness than another type had less end hardness and vice versa.
Also, note that these are measures at a rather unhelpful '12% moisture content'. Why unhelpful, well - again, on that site (being about firewood) it described how there are several different ways of expressing moisture content of wood using percentages. They vary from weight of green versus 'dry' wood through to proportion of remaining wood which is wood fibres versus water. Without knowing which test is applied it would impossible to compare as to whether this data is accurate as to 'dried' wood used in luthierie etc
Actually BRW sure does crack more readily than IRW doesn't it? So perhaps it's not that innacurate.
Of course, science can only take us so far - I suppose the final acid test is the ole 'caveman test' - so which of you guys/gals with stock of IRW and BRW fancies smacking a few planks of each against each other to see which one breaks first?...
